Process for drying sodium carbonate peroxide

Abstract

Manufacturing dry, free-flowing crystalline sodium carbonate peroxide by passing a gas stream at a temperature between 70° and 150° C into a drying zone containing moist sodium carbonate peroxide while maintaining the exit gas stream temperature between 50° and 130° C until the sodium carbonate contains between 0.05% and 0.5% by weight moisture, immediately passing the dried material into a cooling zone where the sodium carbonate peroxide temperature is lowered to between 0° and 40° C, and removing a dry, free-flowing, crystalline sodium carbonate peroxide product containing between 0.001% and 0.20% by weight moisture.

What is claimed is: 
     
       1. In a process of manufacturing a dry, free-flowing, crystalline sodium carbonate peroxide product by reacting hydrogen peroxide and sodium carbonate in an aqueous medium, crystallizing, recovering and drying the resulting moist sodium carbonate peroxide product, the improvement in reducing the loss of active oxygen during drying which comprises: a. passing the moist sodium carbonate peroxide into a drying zone, passing a heated gas stream at a temperature between 70° and 150° C into said drying zone, maintaining the temperature of the exit gas from said drying zone at a reduced temperature between 50° and 130° C, maintaining the sodium carbonate peroxide within said drying zone in contact with said heated gas stream until the sodium carbonate peroxide contains between 0.05 and 0.5% by weight residual moisture;   b. rapidly cooling the hot sodium carbonate peroxide by passing the dried sodium carbonate peroxide into a cooling zone, passing a gas stream at a temperature between -20° and 40° C into said cooling zone, maintaining the temperature of the exit gas from said cooling zone at an increased temperature between 0° and 50° C; maintaining the sodium carbonate peroxide within said cooling zone in contact with said gas stream until the sodium carbonate peroxide is cooled to between 0° and 40° C, and the sodium carbonate peroxide has a lowered residual moisture content, and recovering the cooled material as a stable, dry, free-flowing, crystalline sodium carbonate peroxide product containing between 0.001% and 0.20% by weight residual moisture.   
     
     
       2. The process of claim 1 which comprises removing particles of dry sodium carbonate peroxide from said drying zone and cooling zone exit gases. 
     
     
       3. The process of claim 1, wherein the temperature of the gas stream passing into the drying zone is between 75° and 130° C and the exit gas temperature is maintained between 50° and 80° C. 
     
     
       4. The process of claim 1 wherein the sodium carbonate peroxide is maintained in the drying zone until it contains between 0.10% and 0.25% by weight residual moisture.